The current technology for diagnosing degenerative diseases focuses on blood factors that are commonly associated with normal immune responses. Since these blood factors are associated with normal immune responses, such biomarkers do not provide an accurate prediction of the occurrence of degenerative diseases. Therefore, there is a need for a more specific biomarker for diagnosis of degenerative diseases.
The protein Src homology 3 binding protein 5 (SH3BP5 or SAB) is a scaffold protein found on the outer mitochondrial membrane of mammalian cells. SAB coordinates signaling components on the outer mitochondrial membrane; these components can drive processes such as mitochondrial dysfunction and cell death. For example, increased level of SAB in a cell indicates a significant amount of mitochondrial damage in the cell. Significant mitochondrial damage in a cell ultimately leads to cell death. SAB protein is also implicated in the pathophysiology associated with Parkinson's disease, acetaminophen toxicity, heart attack, and ischemic injury.
SAB acts early during degenerative diseases to prepare the cell for cell death which leads to tissue damage later in the progression of the disease. The mechanism of cell death and tissue loss may involve SAB organizing the signaling components that destabilize the integrity of the mitochondrial membrane and membrane potential. This destabilization may reduce metabolic efficiency and recruit death inducing proteins to the mitochondrial surface. SAB levels also change in response to chronic stress associated with a number of degenerative conditions.
Accurate identification of cancers susceptible to apoptosis inducing chemotherapies or radiation therapies is of great importance when physicians evaluate treatment options for their patients. Therefore, a need exists to identify factors within tumors that may indicate a cancer's vulnerability to current chemotherapeutic approaches. Using SAB as a biomarker for primed mitochondria, one can identify cancers with early-primed mitochondria as being amenable to treatment via chemotherapy.